340 exhaust manifold

[73chalngr]

Does anyone know the correct size of the bolts for the exhaust flange for a 340 with the 1970 manifolds . My gasket failed and my bolts seem a little small the nut side had washers  and the washers are bent a little bit Like they were undersized  bolts and nuts .

[Rich G.]

The flange bolts are 7/16 . The manifold to head are 5/16

[Topcat]

It's true you don't need gaskets and just use a sealer.

Some like using an exhaust gasket.
If you decide to, use the Cometic Copper ones.

They work excellent and seal very well and don't burn out.

[Dakota]

unless you have the heat sheild gasket on the left side you are far less likely to have a leak if you do not use a gasket & just a thin layer of Ultra copper silicone sealer instead , Gaskets cause leaks

I have the heat shield.   Ultra copper on both sides of the heat shield, gaskets on both sides, or something else?

[Chryco Psycho]

just Ultra copper on both sides of the shield

[Morty426]

How come you guys keep taking about the shield and how the manifold attaches to the head?

This guy want to know the size of the flange bolts - manifold to exhaust pipe. 

[73chalngr]

Thanks for responding . Way back in 1990 when my motor was put together we had no idea what to do so I think we used a set of header gaskets we had  .